Apr 16

Connecting Brocade switches to Cisco switches using PVST and PVST+

In order to get a Brocade switch to work well with a Cisco Switch while using PVST/PVST+, there is a little bit of extra configuration to do on the Brocade switch.

Per VLAN Spanning Tree (PVST) is a Cisco proprietary protocol that allows a Cisco device to have multiple spanning trees. The Cisco device can interoperate with spanning trees on other PVST devices but cannot interoperate with IEEE 802.1Q devices. An IEEE 802.1Q device has all its ports running a single spanning tree. PVST+ is an extension of PVST that allows a Cisco device to also interoperate with devices that are running a single spanning tree (IEEE 802.1Q).
The PVST+ support allows the device to interoperate with PVST spanning trees and the IEEE 802.1Q spanning tree at the same time.

If you are not familiar with Brocades configuration, you may want to click here to take a look at some more configuration examples. It’s a little different then Cisco, but not much.

Here you will see the configuration of a Brocade TurboIron connecting to a Cisco Catalyst 6500 using a trunk port (802.1q).

Brocade TurboIron Config

default-vlan-id 3999

vlan 2 name SERVER-VLAN by port
tagged ethe 2
spanning-tree 802-1w

vlan 3 name USER-VLAN by port
tagged ethe 2
spanning-tree 802-1w

interface ethernet 2
port-name To the Cisco Catalyst
dual-mode 1 —> VLAN 1 to match the native vlan of the Cisco
ip-port-mtu 1500 —> Set your MTU to match the Cisco’s MTU on that port
spanning-tree 802-1w admin-pt2pt-mac
pvst-mode —> Tells the switch to use PVST-MODE on this port only

Cisco Catalyst 6500 Configuration

vlan 2
vlan 3

interface TenGigabitEthernet9/5
description To the Brocade FastIron
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 2,3
switchport mode trunk

Here is an example of how you can view what ports on the Brocade Switch are running PVST Mode.

SSH@Goat-Switch#show span pvst-mode
PVST+ Enabled on:
Port Method
2 Set by configuration —> This port is in PVST-Mode due to an interface configuration
4 Set by auto-detect —> This port is in PVST-Mode because it auto detected it

Reference: http://www.brocade.com/downloads/documents/html_product_manuals/BIRX_02900a_CFG/wwhelp/wwhimpl/common/html/wwhelp.htm#href=STP.14.4.html&single=true

What problems have you had with interconnecting Brocade switches with Cisco Switches?
If you had a problem, what did you do to resolve it?

Apr 09

Connecting Dual Cable Connected Servers

I prefer to setup servers that can do cable redundancy with LACP, using either Brocade’s MCT or Cisco’s VPC technology. If you are not familiar with these terms, MCT is Multi-Chassis Trunking, while VPC is Virtual Port Channel. These two technologies perform a similar functions. They allow two switches to perform a LAG or Etherchannel to a single device like a server or another switch.

Servers that have dual connections, I try to connect them to the same port on each of the two switches. This makes it easy to figure out what port on the other switch the server is connected to. I feel this is the best way to provide redundancy to servers with cable redundancy. Using LACP with MCT or VPC gives the server double the bandwidth and eliminates the possibility of a spanning tree loop through the server…. Yes, I have had this happen before.

When I have systems that consist of two servers that are single cable connected, I still connect them over the two switches, on the same port numbers. I don’t have to worry about loops because they are two separate servers. Cisco’s CUCCX servers are a good example of this. This system is so important that we have a second server. If one switch fails the application will fail over to the other server and keep the system up and running.

What about those single cable connected server? I prefer to connect them to a single layer 2 switch with redundant power, redundant management module and redundant switch fabrics.

How do you prefer to connect your dual homed servers?
Do you keep the ports assignments the same across both switches?
Let me know, I would like to hear from you!!